Problem: If $x \odot y = 2x-7$ and $x \circledcirc y = x-4y$, find $(-4 \circledcirc 0) \odot 0$.
Answer: First, find $-4 \circledcirc 0$ $ -4 \circledcirc 0 = -4-(4)(0)$ $ \hphantom{-4 \circledcirc 0} = -4$ Now, find $-4 \odot 0$ $ -4 \odot 0 = (2)(-4)-7$ $ \hphantom{-4 \odot 0} = -15$.